Strike action by thousands of Spanish and Portuguese truckers produced ominous knock-on effects on food supplies, aviation and industry yesterday, as Lisbon airport ran out of fuel, car factories shut down and petrol stations and supermarkets reported shortages.

In a worrying sign for other European countries that face rising discontent at the spiralling cost of diesel, a third day of strikes generated widespread mayhem and the mood turned ugly after the first casualties of the standoff: two strikers died in clashes on picket lines.

Tourists flying to Lisbon faced delays after the airport ran out of fuel. Some flights were diverted to Porto. Only emergency, military or state flights were allowed out of Portela airport, a spokesman said. Only emergency fuel stocks saved Spanish airlines from similar disruption.

Supermarkets, meanwhile, reported dwindling supplies. Authorities at Spain's two biggest wholesale markets, Mercamadrid, in Madrid, and Mercabarna in Barcelona, reported deliveries of meat, fish and fruit were almost at a standstill.

In Barcelona, at a branch of Caprabo supermarket, there was no fresh fish or meat on the shelves. Shopper María Luz Martínez, 38, said: "The lorry drivers are looking after themselves while we are all suffering. But the government doesn't appear to be that interested."

As panic buying among motorists continued, petrol stations were running dry. Drivers in Lisbon trying to fill up their cars were turned away. In Spain, "empty" signs hung from pumps at hundreds of stations across the country. Three car firms, Seat, Nissan and Mercedes, suspended production because of parts shortages.

Some ferries from the Balearic islands to mainland Spain were cancelled due to lack of fuel. José María Pozancos, director of Spain's fruit and vegetable export federation, said the strike was costing the industry €25m (£20m) a day.

The action is being closely watched in France, Italy, Britain and other countries where the threat of a similar strike looms. Diesel prices have shot up on average around 40% over the past year amid record jumps in oil prices, and truckers say profits have been all but wiped out. Italian hauliers are planning a five-day strike at the end of the month, while their British counterparts are targeting central London again on July 2.

With unions talking of coordinated action in several countries at a time and policymakers in Brussels refusing to countenance tax breaks, the fear is that the action in Spain and Portugal could spread. Yesterday truckers in Thailand used a half-day strike to demand financial help.

As the Spanish government yesterday deployed 25,000 police to clear major routes, the mood among strikers was increasingly turning bitter. Scores of pickets were arrested in clashes with police and two drivers were killed at blockades.

Lorry driver Julio Cervilla Sojo, 47, a father of two, died after being run over by a lorry which was trying to pass picket lines near Granada on Tuesday. A man was arrested and appeared in court.

In Portugal, a 52-year-old man was killed on a picket line north of Lisbon, as he tried to stop a lorry passing a blockade.

Picketers in Spain have thrown stones at lorries trying to pass blockades. One driver suffered serious burns near Alicante when four trucks were set on fire.

Hooded strikers in Valencia were photographed brandishing knives. Riot police cleared pickets blocking routes into major cities and the La Junquera junction between Catalonia and France.

Alfredo Pérez Rubalcaba, the Spanish interior minister, said 51 people were arrested after violence on picket lines. He said: "There is a constitutional right to strike. There is no constitutional right to disrupt people's lives. Therefore, we are going to continue acting with maximum force and maximum firmness."

For Spain's prime minister, José Luis Rodríguez Zapatero, who is already facing a downturn in the economy since the end of the building boom, the strike is the most serious bout of industrial unrest since he took power in 2004.

About 70,000 mostly self-employed drivers from two unions, which make up about 20% of the industry, are demanding guaranteed haulage rates so they can offset rising fuel prices. But the government, which has offered tax concessions to the lorry drivers, opposes fixing guaranteed rates, saying it would be against EU free-market principles.